1. Field of the Invention
The present invention relates generally to an improved flow control device and in particular to an improved flow control device for use in regulating flow of particulate matter. This invention relates generally to solid granule or powdered material throttling gates particularly used in the bottom of holding or weighing hoppers and for controlling the flow through connecting spouting.
2. Description of the Prior Art
Throttling type solid and powdered material control valves are characterized by an ability to precisely control unidirectional flow through a flow opening, or openings, which are generally adjustable in size to suit the needed flow capacity. Such valves may be suitable for controlling grains of all types, granule, and certain powdered type materials (hereinafter collectively referred to as "particulate matter"). Prior art gates are grouped into "slide type" and "butterfly type" designs.
Slide gates consist of two similar frames held apart by the thickness, plus clearance, of a solid plate that is made to slide between the two frames. When the plate is positioned between the frames, the gate is closed and will not allow any material to flow through the frames. When the plate is pulled out from the frames, the material will pass through where the plate had been. The outside part of the frame has to support the plate and any material that will be resting on the plate when loaded. The plate has to be heavy enough to support any material that will be resting on it. The length or width of the plate determines the strength and length of the power device that is used to move the plate to open and close it in the frame. The larger the plate gate the stronger and longer the power device has to be, on a direct proportional basis. The larger the gate the longer the time required to open and close the gate. This does not allow for good control of the gate opening and closing for any position between fully closed or fully opened.
Butterfly gates consist of a round frame with two round solid shafts mounted on the outside perimeter of the frame. It is perpendicular to the opening axis, 180 degrees from each other. The gate plate consists of several overlapping plates that are hinged at one end on the round shafts. Half of the plates are mounted on one shaft and the other half are mounted on the other shaft is the opposite. The plates are rounded in shape on the outside edge so that when the gate is closed the plate matches the circumference of the frame. When the gate is closed the gate plates mesh together from both directions and close off the opening. When the gate is open the plates separate and swing back away from the opening. This type of gate is expensive to make and is limited as to the amount of weight the moving plates can support.